‘Green’ alternative to road salt
Bastiaan Bakker & Raksha Kishna – ATR8
13-04-2011
‘t Atrium, the Netherlands
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Summary
There are several commonly-used chemicals to melt ice.The use of road salt as a de-icer on roads
and other surfaces is the preferred method to promote safe motor vehicle and pedestrian travel
during winter months. Since the most commonly used de-icing salt NaCl(s) has negative effects
on the environment, it raises the question whether the use of more eco-friendly alternatives to
harmful chemicals, such as road salt, is possible to function as de-icer to melt the ice. The natural
fertilizer alfalfa meal is said to be an environmentally friendly way to melt ice. Comparing the
melting of 50 grams of H₂O(s) with 5,0 grams of alfalfa meal seemed to cause the ice to melt
faster but due to unreliable measuring results it is hard to tell whether it will be effective enough
to function as a useful de-icer. Although it is less effective when comparing to the melting of 5,0
grams of NaCl(s), it certainly is a more environmentally friendly alternative.
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Introduction
The most commonly used de-icing salt is
sodium chloride NaCl(s), which is readily
available and inexpensive and effectively
depresses the freezing point of water to
melt ice. Although, if used excessively, it can
be harmful to pets, plants, metal, and the
environment. This raises the question: what
is a more environmentally friendly
alternative to road salt?
According to different informative sources,
such as various web sites [1], experiments
and people’s personal experiences, alfalfa
meal is an environmentally friendly way to
melt ice. Although not well-known, alfalfa
meal, usually used as a fertilizer, has a
strong nitrogen content which supports ice
melting. Additionally, it provides traction.
It's biodegradable and it not only doesn’t
harm the environment by burning the
landscapes like salt and some of the other
de-icers, it fertilizes it instead.
We expect the ice to melt because of the
natural fertilizer alfalfa meal. We think this
completely natural product contains
nitrogen which binds H+ and releases
hydroxides promoting the ice to melt.
3 H2O + N + 3 e-  NH3 + 3 OHFurthermore, it has a texture to provide
traction. We expect the alfalfa meal to act
fast and effective enough to be a good
alternative de-icer to road salt.
Experimental design
With this inquiry we want to compare the
melting process of H₂O(s) with alfalfa meal
to the melting of H₂O(s) without any
substances added to conclude whether the
use of alfalfa meal will be successful as a deicer. We will also compare the melting of
H₂O(s) with common road salt to the ecofriendly alternative alfalfa meal to find out
whether the use of alfalfa meal will be
suitable and effective enough to replace
ordinary road salt.
For the set-up, we took four identical
graduated cylinders and four identical
funnels which were placed on top of the
cylinders, left at room temperature. 50
grams of crushed ice cubes were put into
Results
Every 10 minutes we noted down the
amount of water that appeared in the
graduated cylinders. The measurements for
the melting processes of the ice with and
without alfalfa meal and with NaCl(s) are
presented in the following table.
Time (in
minutes)
0
10
20
30
40
50
60
70
Without
NaCl/
alfalfa
meal
(mL)
0
15
25
33
40
44
47
50
With
alfalfa
meal
(mL)
With
NaCl(s)
(mL)
0
13
20
26
34
36
37
-
0
20
35
41
46
51
-
Table 1: Amount of melted ice (mL) with
alfalfa meal, NaCl(s) and without
60
Melted ice (mL)
each funnel. In two set-ups 5,0 grams of
alfalfa meal was added to the crushed ice, in
the third set-up the funnel was filled with
5,0 grams of NaCl(s) and to the last set-up
nothing was added.
From the moment the crushed ice, salt and
alfalfa meal were placed into the funnel, the
time of the melting process was recorded.
Using the graduated cylinders with a
division of 2 mL, the speed of the melting
processes can be followed easily by reading
off the measurements.
There were several conditions which we
had to take into account. We had to look at
the dependent, independent and controlled
variables. The independent variables were
the amounts of alfalfa meal and road salt
used to show in which ratio the melting
process will be most successful. The
dependent variable was the melting process
of the ice. The controlled variables, which
we kept steady, were the temperature,
humidity and the amount of crushed ice
being used. We’ve weighed the amounts of
ice, alfalfa meal and NaCl(s) to make sure
the independent variables wouldn’t affect
the reliability of the dependent variable.
Without
NaCl/alfalfa
meal
With alfalfa
meal
50
40
30
20
10
With NaCl
0
0 10 20 30 40 50 60 70
Time (in minutes)
Figure 1: Measured amount melted ice (mL)
with alfalfa meal, NaCl(s) and without
Conclusion and discussion
Our main question whether or not there
would be a more environmentally friendly
alternative to road salt hasn’t fully been
answered. As is shown in Figure 1 the
melting process of the crushed ice with
NaCl(s) started immediately and has been
most effective, whereas the other two
processes started more slowly and
eventually had a less effective result.
The melting process with alfalfa meal in this
figure looks like as if it has even been less
effective than normal ice. This is not the
case. The crushed ice with alfalfa meal
added seemed to melt faster, but since the
alfalfa meal itself absorbed the water, the
measurements of the graduated cylinders
are considered unreliable. This wasn’t
exactly the result we had expected.
Furthermore the results haven’t been
influenced by other factors, since the
controlled variables were kept constant and
the independent variables and the crushed
ice have been weighed precisely. Although
the temperature was kept constant, it still
cannot be considered realistic since there
won’t be any ice formation at a room
temperature of approximately 20°C. This
might have influenced the results and makes
the measurements less reliable.
Evaluation
This experiment didn’t come up to our
expectations, but it did raise further
questions and supported us to come up with
possible improvements.
For this experiment, the set-up wasn’t as
successful as we thought it would be.
Because the alfalfa meal absorbed the water,
the measurements of the graduated
cylinders were practically useless. To make
sure the results of this experiment are
reliable, this inquiry will have to be tested in
another set-up.
When we look at the variable temperature,
the reliability of this inquiry is also
questioned. Since there is no ice formation
at a temperature of 20°C, but is more likely
to happen around 0°C, the measurements of
this experiment might be different from the
results when the experiment would have
been done at a temperature of 0°C. This
could be simulated in a polystyrene box
filled with ice cubes for instance.
According to many sources [1], the alfalfa
meal is said to provide traction as well. This
raises further questions for inquiry: does
alfalfa meal provide traction? Does it leave
behind a lot of waste products and how do
we get rid of it?
We also expected hydroxides to promote ice
melting, but this hasn’t been proved in this
inquiry. This can additionally be shown in
another experiment to prove the hydroxides
actually promote ice melting or not.
Whatever solution can be found, we can
conclude from the experiment results that
alfalfa meal might be an alternative de-icer,
but to confirm this more experiments are
required. Although the results hardly
answer our main question, one thing is for
sure, alfalfa meal is certainly more
environmentally friendly than NaCl(s).
Bibliography
- [1] http://www.paystolivegreen.com/
2009/12/eco-friendly-deicers/;
- http://greenlivingqa.com/content/de-icer;
- http://www.sustainabilityconsulting.com/
blog/2010/3/1/views-eco-friendly-deicing-alternatives-to-salt.html;
- http://en.wikipedia.org/wiki/Sodium_chlo
ride
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Practical Assignment Chemistry ICY – road
salt, VU Amsterdam The Netherlands,
January 2011